Barcelona-based builder Fomento de Construcciones y Contratas (FCC) SA's shares rose by as much as 8.8% on Friday on reports that billionaire financier George Soros had bought a 3% stake from the company's founding family.

According to a report by Reuters, this would be the second high-profile purchase in FCC by a foreign investor this year. Microsoft Corp. founder Bill Gates bough a 6% stake in the construction company in October. Soros controls American hedge fund Soros Fund Management LLC.

Loss-making FFC has cut staff and put assets like its real estate division Realia up for sale. The Spanish builder has also made big writedowns on its renewable energy business and its insolvent Austrian construction company Alpine to cut debt, the report said.

FCC said that its founding Koplowitz family sold 3.8% of its controlling stake in the company for €72 million ($98.59 million) to reduce personal debt. The household maintained an ownership of just over 50% of the construction firm, Reuters said.

FCC's net debt stood at €6.6 billion at the end of September. This is more than three times is market valuation, the report said.